Wheelbarrows are useful to carry heavy loads manually. They generally include a tray or bin, at least one wheel, and a frame having a pair of legs and a pair of handles attached thereto. A wheelbarrow is moved by lifting its handles to raise the legs off the ground, balancing the wheelbarrow on its wheel, and then walking while pushing or pulling the handles to a desired direction. A wheelbarrow is typically unloaded by dumping, i.e., lifting the handles to tip the bin into a vertical position where the load slides out the sloped front end portion of the bin.
Wheelbarrows are typically used to move loads across uneven ground, and/or soft surfaces such as floors or roofs. Wheelbarrows are also useful due to their ability to easily dump the load. However, as the weight of the load increases, it becomes more difficult to balance the wheelbarrow, particularly during the dumping process. Also, in order to dump the load out of the bin completely, the worker is often required to shake and rock the wheelbarrow back and forth, sometimes tilting the bin over a vertical position.
To improve the maneuverability during a dumping operation, several designs and modifications to a wheelbarrow have been suggested. For example, U.S. Pat. No. 5,026,079 to Donze et al. discloses a wheelbarrow having multiple wheels and a horizontal circular abutment member positioned in front of the wheels. The abutment member is in horizontal alignment with the axles of the wheels and serves as a fulcrum for tipping the wheelbarrow. The abutment member also assists the wheelbarrow to be balanced in a vertical storage position resting on the abutment member and the straight front edge of the tray. However, the multiple wheels of Donze et al. wheelbarrow increase weight and affect maneuverability during the dumping operation (and also during the movement of the wheelbarrow toward a desired direction). Furthermore, the circular abutment member is firmly welded to the arms to provide the required strength to endure the heavy weight of the wheelbarrow and the load, thus lacking interchangeability of the abutment member to replace with other abutments having different configurations as desired to meet different work environments.
Another example to improve the dumping operation is described in U.S. Pat. No. 5,601,298 to Watanabe. Watanabe discloses a wheelbarrow having a wheel, a pair of arms, a front guard firmly affixed to the pair of arms, and a pair of roundish handle grips for facilitating the dumping operation. One embodiment of the front guard shows a pair of roundish bars extending downward from the rounded front bar (FIG. 9). Another embodiment of the front guard suggests a curved plate firmly affixed to the pair of arms and extending (only) downwardly with respect to the pair of arms (FIGS. 8A and 8B). As is similar to Donze et al. discussed above, upon permanent fixing of the front guard to the arms, Watanabe wheelbarrow lacks interchangeability of the front guard member to replace with other abutments having different configurations to be used as desired. Furthermore, the front guard extends only downward from the arm shafts to which the wheel is mounted. Accordingly, this front guard configuration does not provide continuous support when pushing and tilting beyond the vertical position, and may be slippery due to decreased friction against the ground by standing only on the edge line of the front guard, thus often losing the balance and falling over to the ground. Otherwise, the edge of the front guard may dig into the ground surface causing damage to the ground structure, which may be of particular concern when dumping on soft surfaces, such as wooden floors and roofs.